In a conventional glass sheet bending system including a furnace having a bending section and a topside support device, a glass sheet is received by the topside support device which includes a downwardly facing surface for receiving the glass sheet prior to release onto a glass sheet shaping tool such as a lower mold used for forming the glass sheet. The glass sheet is supported on the topside support device prior to being deposited onto the lower mold.
Pressurized gas is used to prevent surface-to-surface contact and to assist in conveying the glass sheet. Inertia of the glass sheet moving in a plane of conveyance in the furnace provides movement of the glass sheet supported on the topside support device. Because of the relative velocity of the glass sheet, the glass sheet experiences an abrupt engagement as it is brought to an at rest position on the topside support device. In one arrangement, a mechanical stop is mounted on the topside support device to restrain the moving glass sheet. The abruptness of the engagement often causes the glass sheet to bounce off the stop. Thereafter a back gate assembly is moved into position at the upstream end of the glass sheet to hold the glass sheet in its at rest position.
In another embodiment, a mold as taught in U.S. Pat. No. 4,775,404 having a plurality of glass sheet locators is used to stop and position the glass sheet for subsequent registration with the mold surface. The vacuum drawn by the topside support platen is terminated and the glass sheet is deposited on the lower mold below the topside support device.
Such mold apparatus is expensive and requires extensive maintenance. When bending glass sheets for subsequent lamination, time consuming manual adjustment of the glass sheet locators must be made so that two differently sized glass sheets, one inner and one outer, can be bent to the same shape for subsequent lamination. When the mechanical stops are used with an air float conveyor, the heat induced growth of glass restraining bars inhibit the accuracy of alignment of the glass sheets on the topside support device.